Sitting at your desk all day or on your sofa watching TV could make you stupid, scientists have suggested.

科学家指出，终日坐在桌前或者坐在沙发上看电视会让你变傻。

Researchers have discovered those with a sedentary lifestyle have a smaller brain region important in forming memories.

研究人员发现，那些习惯久坐的人的大脑中负责形成记忆的区域更小。

The study, by researchers at the University of California at Los Angeles, adds to a growing list about the dangers of sitting for too long.

长期久坐的危害有很多，洛杉矶加利福尼亚大学的研究人员开展的这项研究又揭示了久坐的一个新危害。

An array of evidence has already linked the bad habit to heart disease, diabetes¹, several forms of cancer and an early death in recent years.

近些年有大量证据显示，久坐这一坏习惯和心脏病、糖尿病、几种癌症和早逝有关。

But the new research, derived² from 35 participants, suggests sitting for too long could even boost the risk of dementia.

新研究调查了35名参与者，结果显示，久坐甚至会增加患老年痴呆症的风险。

Those with the lazy lifestyles had less grey matter in the medial temporal lobe³ (MTL) - even if they went for regular brisk walks, cycle rides or jogs.

经常久坐不动的人即使定期快走、骑车或慢跑，大脑内侧颞叶的灰色神经组织也比不久坐的人更少。

A decline in this area has repeatedly been shown to be an early warning sign of Alzheimer's disease in middle-aged⁴ and elderly patients.

中老年人大脑内侧颞叶的萎缩已被反复证实是患上老年痴呆症的早期迹象。

The study, published in PLOS ONE, quizzed the volunteers, who were aged between 45 and 75, about their levels of exercise.

这项发表在《公共科学图书馆·综合》期刊上的研究对年龄在45岁到75岁之间的志愿者就其锻炼水平进行了问卷调查。

Each person underwent a high-resolution MRI scan which provides a detailed⁵ look at the MTL, an area involved in the formation of new memories.

每个人都接受了高分辨率核磁共振成像扫描，研究人员还仔细查看了他们的大脑内侧颞叶——负责形成新记忆的区域。

The researchers, led by biostatistician Dr Prabha Siddarth, found that sedentary people had a thinner MTL.

生物统计学家普拉布哈·西达斯博士领头的研究团队发现，久坐的人大脑内侧颞叶更薄。

Dr Siddarth and colleagues revealed how this finding remained true - even when volunteers had high levels of physical activity.

西达斯博士和他的同事指出，即使志愿者运动量大，这一结果也不会改变。

The researchers warned that the study 'does not prove too much sitting causes thinner brain structures'.

研究人员警告说，该研究“没有证明久坐会导致大脑内侧颞叶变薄”。

However, they were keen to add the research does prove 'that more hours spent sitting are associated with thinner regions'.

但是，他们马上补充道，研究确实证明“久坐和大脑内侧颞叶变薄有关”。

The researchers wrote: 'MTL thinning can be a precursor⁶ to cognitive⁷ decline and dementia in middle aged and older adults.

研究人员写道：“大脑内侧颞叶变薄预示着认知能力的下降和中老年痴呆。”

'Reducing sedentary behaviour may be a possible target for interventions⁸ designed to improve brain health in people at risk for Alzheimer's disease.'

“减少久坐时间也许是一个可以帮助老年痴呆风险人群改善大脑健康的目标介入手段。”

The scientists, who were part funded by the US government, now plan to follow up the preliminary findings on a larger trial group.

现在科学家计划在初步研究结果基础上继续开展这项研究，扩大试验范围。这项研究的资金部分来源于美国政府。

This will help determine if sitting causes the thinning and what precise role gender⁹, race and weight may play, they said.

他们表示，这将有助于确定久坐是否导致大脑内侧颞叶变薄，以及性别、种族和体重有无影响。

Previous research shows physical activity correlates with higher volume in the hippocampus, a small, memory-critical region deep within the brain.

先前的研究显示，身体活动与更大的海马体有关，海马体是大脑深处和记忆密切相关的一小块区域。

The temporal lobes¹⁰ are on either side of the brain, near the temples. They deal with memory, including recognition of faces and objects, and language.

大脑两侧临近太阳穴的颞叶掌管着记忆，包括对脸、物体和语言的辨识。

The Alzheimer's Society said: 'Our day-to-day memory of personal experiences, known as episodic memory, is very closely linked to the hippocampus.'

阿尔茨海默氏病协会表示：“我们每日关于个人经历的记忆叫作情景记忆，和海马体的关系十分紧密。”

They added that this is 'inside the temporal lobe on each side of the brain'.

他们补充说，这部分记忆就储存在“大脑两侧的颞叶之内”。

'The outer part of each temporal lobe is where we store general knowledge, which is a different type of memory known as semantic memory,' a spokesperson said.

该协会的一名发言人说：“每侧颞叶的外围部分就是我们储存常识的地方，这是另一种记忆，名为语义记忆。”

'The left temporal lobe usually deals with facts, the meanings of words and the names of objects. This lobe is central to understanding speech and talking.

“左侧的颞叶通常储存事实、词语的意思和物体的名字。这一侧颞叶对于理解言语和谈话至关重要。”

'The right temporal lobe usually deals with visual material. This lobe is central to recognising familiar objects and faces. '

“右侧的颞叶通常掌管视觉信息。这一侧颞叶对于辨识熟悉的物体和脸很关键。”